Human Anatomy and Physiology-I, Special senses: Structure and functions of eye, ear, nose and tongue and their disorders.

1. BP101T. Human Anatomy And Physiology-I
(Theory)
Unit-IV
2. Special Senses
Represented By,
Mr. Audumbar Mali.
(Assistant Professor)
Sahyadri College of Pharmacy
Methwade

2. 1. Eye,
2. Ear,
3. Tongue,
4. Nose.

3. Introduction
• Our “senses” continually provide us with
information about our surroundings.
• Sense organs are complex organs like
the eye or specialized receptors in areas
such as the nasal mucosa or tongue.

4. Introduction
• Conversion of a stimulus to a sensation:
– Stimuli (light, sound, temperature, etc. are
changed into an electrical signal or nerve
impulse.
– The signal is then transmitted over a neuron.
– The signal is interpreted and we become
consciously aware of a sensation.

5. 1. Eye
• Contains receptors for vision and a
refracting system that focuses light rays on
the receptors in the retina.
• The eye sits in the orbit formed by the
maxilla, zygomatic, frontal, sphenoid and
ethmoid bones. Extrinsic muscles attach
the surface of the eyeball to bones.

6. How it is work:-
1. Light Rays bounce off an object you are looking at.
2. Light then enters through the outer part of the eye, called the cornea.
3. Next, light rays go through an opening called the Pupil.
4. Light passes through the lens on its way to the back of the eye.
5. The retina sees the world upside down, but the Brain turns it right side
up.
6. When you look at an object, each eye sees a slightly different picture.
The brain combines the images into one picture.

7. The Eye
• Eyelids – contain skeletal muscle that allow us to
close them and totally cover the exterior eyeball.
• Eyelashes – help to keep dust out of our eyes.
• Tears

10. The Eye
• Cranial Nerves
– Optic – vision
– Oculomotor, abducens and trochlear – eye
movment

12. The Eye
• Structure of the eyeball
– Sclera – tough fibrous tissue.
• Front surface is the “white” of our eyes and the
cornea. The cornea is transparent, receives no
blood supply and is nourished by the aqueous
humor.
• Sclera is covered by the conjunctiva in the front of
the eyeball.

13. The Eye
• Structure of the eyeball
– Choroid - contains a dark pigment to prevent
scattering of light that enters the eyeball. Also
contains blood vessels and 2 involuntary
muscles.
• Iris –
• Ciliary body (muscle) –

14. The Eye
• Structure of the eyeball
– Lens – composed of transparent, elastic
protein; no blood supply, nourished by the
aqueous humor.
– Retina – contains microscopic receptor cells
called rods and cones.
• Rods –
• Cones –
• Fovea –

15. The Eye
• Layer of the eye
– Retina
• Ganglionic neurons carry impulses generated by
the rods and cones until they converge at the optic
disc. From the optic disc they form the optic nerve
and pass through the wall of the eyeball to the
occipital nerve.
• Optic disc – also know as the “blind spot”, no rods
or cones; exit to the optic nerve.
• Occipital lobe of the cerebrum – visual
interpretation.

17. The Eye
• Structure - fluids of the eyeball – 2
types:
– Aqueous humor – watery fluid in front of the
lens (anterior cavity) nourishes the lens and
cornea.
• Continually formed by the capillaries in the ciliary
body, flow through the pupil and is reabsorbed in
the canal of Schlemm.
• If drainage is blocked, the internal pressure in the
eye increases and may damage the eye and lead to
blindness = glaucoma.

18. The Eye
• Structure - fluids of the eyeball – 2
types:
– Vitreous humor – jelly-like fluid behind the
lens (posterior cavity). Literally holds the
retina in place and gives structure to the
eyeball.

19. Disorders of Eye:-
• 1. Glaucoma is a disease of the eye in which
fluid pressure within the eye rises; if left
untreated, the patient may lose vision and even
become blind. Glaucoma is relatively common,
especially in older adults and can cause damage to
the optic nerve if left untreated.
• In short, glaucoma is a build up of pressure
within the eye that causes damage to the optic
nerve.

20. • 2. Conjunctivitis, also known as
pinkeye, is an inflammation of the
conjunctiva. The conjunctiva is the thin
clear tissue that lies over the white part of
the eye and lines the inside of the eyelid.
• 3. A stye is an inflammation of the
eyelid associated with a small collection
of pus. In most cases, the infection is
caused by the Staphylococcus bacteria. It
is sometimes known as a hordeolum.
Although uncomfortable and incredibly
common, styes are not generally a cause
for concern.

21. • 4. Trachoma is an infectious disease
caused by bacterium Chlamydia trachomatis.
The infection causes a roughening of the
inner surface of the eyelids. This roughening
can lead to pain in the eyes, breakdown of
the outer surface or cornea of the eyes, and
eventual blindness.
• 5. Retinopathy is any damage to
the retina of the eyes, which may cause
vision impairment. Retinopathy often refers
to retinal vascular disease, or damage to the
retina caused by abnormal blood flow.
Diabetes is the most common cause of
retinopathy.

22. 2. Ear
• Sense organ associated with hearing
and equilibrium and balance.
• 3 main parts
– External
– Middle
– Inner

23. The Ear
• External ear –
• External Auditory canal – a curving tube about one
inch long; extends into the temporal bone and end at the
tympanic membrane (eardrum).

24. The ear
• Middle ear – tiny epithelium lined cavity
which is hollowed out of the temporal
bone.
– Tympanic membrane – separates the external
and middle ear and vibrates when sound
waves strike it.
– 3 tiny bones called ossicles (bones) transmit
sound waves.

25. The Ear
• Middle Ear
– Bones
• Malleus –
• Incus –
• Stapes –

26. The Ear
• Middle Ear
– Oval Window separates the middle ear from
the inner ear.
– Eustachian tube – connects the throat with the
middle ear; allows air to enter and leave the
middle ear which equalizes pressure. Why do
throat and ear infections occur together?

27. How it is work:-
1. Sound waves are collected in the outer ear.
2. Sound waves pass through our ear canel and cause our ear
drum to vibrate.
3. These vibrations are sent to our inner ear by the ossicles.
(small bones in the middle ear)
4. The vibrations reach the cochlea. The fluid in the cochlea
begins to move, this motion results in the hair cells sending a
signal along the auditory nerve to the brain.
5. Our brain receives these impulses and interprets them as a type
of sound.

29. The Ear
• Middle Ear - Hearing Sequence
– Sound waves cause the eardrum to vibrate,
and this movement is transmitted and
amplified by the ear ossicles.
– Movement of the stapes against the oval
window causes movement of fluid in the inner
ear which generates electrical impulses.

30. The Ear
• Inner Ear – contains mechanoreceptors
that are activated by vibration and
generate nerve impulses that result in
hearing and equilibrium. The 3 spaces are
called the bony labyrinth and contain fluids
called perilymph and endolymph.
– Vestibule – membranous sacs (utricle and
saccule) adjacent to the oval window and
between the semicircular canals. Contains
receptors for equilibrium.

31. The Ear
• Inner Ear
– Cochlea – snail shell; contains the Organ of
Corti which holds the receptors for hearing
(hair cells). As the hairs bend (vibration) they
generate an electrical impulse.
– Semicircular Canals – contain the crista
ampularis which is a specialized receptor that
generates a nerve impulse when you move
your head. Receptors for equilibrium.

32. Disorders of Ear:-
1. Ear infections:-
• Ear infections are the most common in child,
adults can also get ear infections, but they are less
common.
• The infection usually affects the middle ear
and is called otitis media. The tubes inside the ears
become clogged with fluid and mucus. This can
affect hearing, because sound cannot get through
all that fluid.
2. Tinnitus is often described as a ringing in the ears. It also can
sound like roaring, clicking, hissing, or buzzing. It may be
soft or loud, high pitched or low pitched. You might hear it
in either one or both ears.

33. Causes of tinnitus includes
• Hearing loss in older people
• Exposure to loud noises
• Ear and sinus infections
• Heart or blood vessel problems
• Brain tumors
• Hormonal changes in women
• Thyroid problems
• Certain medicines

34. 3. Tongue:-
• Taste buds – chemical receptors that generate
nervous impulses resulting in the sense of taste.
There are about 10,000 microscopic taste buds
located on the papillae of the tongue.
• Gustatory cells – The gustatory (taste) cells,
which are chemoreceptors, occupy the central
portion of the bud; they are spindle-shaped, and
each possesses a large spherical nucleus near the
middle of the cell. The peripheral end of
the cell terminates at the gustatory pore in a
fine hair filament, the gustatory hair.

35. Sense of Taste
• Taste Sensations
– Sweet, sour, bitter and salty.
– Other flavors results from a combination of
taste bud stimulations and olfactory receptor
stimulation. i.e. our taste sensations include
odors as well.

36. Disorders of Tongue:-
• 1. Tongue cancer is a type of mouth cancer, or oral
cancer, that usually develops in the squamous cells on the
surface of the tongue. It can cause tumors or lesions. The
most noticeable signs of tongue cancer are a sore on the
tongue that does not heal and a painful tongue.
• Symptoms: - pain in the jaw or throat pain when
swallowing feeling as though something is catching in the
throat, stiff tongue or jaw problems, swallowing or
chewing food a red or white patch forming on the lining of
the mouth or tongue, a tongue ulcer that will not heal,
mouth bleeding from the tongue without reason.

37. 4. Nose:-
• Olfactory receptors – chemical receptors responsible
for the sense of smell are located in the upper part of the
nasal cavity.
• Olfactory receptors are stimulated by chemicals
dissolved in the watery mucus that lines the nasal cavity.
We detect about 10,000 different scents.
• Olfactory receptors are easily fatigued – many odors
are not noticeable after a time.

38. Process of Smell:-
- When we breathe, some chemicals enter
our nose
• => chemicals dissolve in the mucus
• => stimulate the smell receptors to
produce messages
• => These messages are sent to the
brain to give us the odor of the food.
Some chemicals in the
food diffuse
into the air.

39. chemicals
in food
sensory
cell
mucus lining
inside
nasal cavity
nerve
Brain

41. • Visceral sensations – receptors are
located in the hypothalamus; the stimulus
is a change in the body’s water/salt
content and levels of nutrients in the
blood.

42. Cutaneous Sensations
• Receptors of the general sense organs
are found in almost every part of the body.
– Encapsulated nerve endings – located in the
dermis; touch and pressure.
– Free nerve endings – mainly in the dermis of
the skin, mucosa, internal organs. They
sense pain or crude touch. *Referred pain.

43. Cutaneous Sensations
• Receptors
– Meissner’s corpuscles – skin, fingertips and
lips; sens of fine touch and vibration.
– Ruffini’s corpuscles – skin and sq tissue of the
fingers; touch and pressure.
– Pacinian corpuscles – subcutaneous; deep
pressure and vibration.

44. Cutaneous Sensations
• Receptors
– Krause’ end bulbs – skin and sq; touch and
maybe cold.
– Muscle spindles – skeletal muscle;
proprioception. Proprioception is the sense of
position and movement in various parts of the
body.

45. Characteristics of Sensations
• Projection – sensation seems to come
from the area where the receptors were
stimulated; in reality they are being “felt”
via the cerebral cortex.
– Phantom pain – receptors are removed with
amputated limbs but severed nerve endings
continue to send impulses to the brain.

46. Disorders of Nose
1. Allergic rhinitis, also known as hay fever, is a
type of inflammation in the nose which occurs
when the immune system overreacts
to allergens in the air. Signs and symptoms
include a runny or stuffy nose, sneezing, red,
itchy, and watery eyes, and swelling around
the eyes. The fluid from the nose is usually
clear.

47. 2. Cerebral spinal fluid leaks: -
A CSF leak is a condition that occurs when
the CSF leaks through a defect in the dura
or the skull and out through the nose or
ear. A CSF leak results from a hole or tear
in the dura, the outermost layer of the
meninges. Causes of the hole or tear can
include head injury and brain or sinus
surgery.

48. References:
1.Human Anatomy and Physiology-I,
By Dr. Mahesh Prasad,
Dr. Antesh Kumar Jha, Mr. Ritesh Kumar
Srivastav, Nirali Prakashan,
As per PCI Syllabus.
Page No. 4.14 to 4.24.
2. www.google.com.

49. THANK
YOU